The original post opened me up to something that I'd never thought of before, not even during the many times in the past where suicide was at the forefront of my mind (more as a moral question than an option). There are indeed a billion motives for suicide, but we only have one word for it, regardless of the circumstances or motives surrounding the death.
Consider how many ways we can describe a death when two (or more) people are involved; murder, assassination, mercy killing, justified self-defense, revenge, manslaughter (say, if one killed another out of carelessness rather than malice). But we don't have many ways to describe the motive behind a suicide. It's just automatically "suicide", and all that implies.
So is this intentional? Do we want to cover all self-inflicted deaths under a blanket term so that people will hear all the negative connotations along with the word? Or is it just a result of the laziness of English speakers in the USA? Clearly other cultures demonstrate an understanding of the differences in suicidal motives (the Japanese seppuku and kamekazi were a great example).